Found in

• Nighty 115.0a1

Affected versions

• Nightly 115.0a1

Tested platforms

• Affected platforms: macOS 12, Windows 10, Ubuntu 20.04.

Preconditions

• in about:config, set the preference "layout.css.font-visibility.private" to 1.

Steps to reproduce

1. Open a private window.
2. Navigate to Wikipedia and look for Miscellaneous Technical.
3. Observe the symbols.

Expected result
All the symbols should be properly displayed in Private Browsing.

Actual result
Tofu boxes are displayed for some of the symbols. Look for: power symbol, power on-off symbol, power on symbol, and power sleep symbol.

Regression range
This is not a regression, the font visibility preference is set to 3 on all previous versions: ESR, Beta, and Release.

Additional notes

• The tofu boxes are also displayed when the preference "layout.css.font-visibility.private" is set to 2.
• The tofu boxes are not displayed in normal browsing or when "layout.css.font-visibility.private" is set to 3.

:sbadau, if you think that's a regression, could you try to find a regression range using for example mozregression?

Hi Simona,

About the missing fonts, is the whole block showing tofu boxes or just some individual (rare/recently-added?) characters?

And is the behavior consistent across different platforms?

Thanks.

(In reply to Tim Huang[:timhuang] from comment #2)

Hi Simona,

About the missing fonts, is the whole block showing tofu boxes or just some individual (rare/recently-added?) characters?

Only some individual characters, like:

• power symbol
• power on-off symbol
• power on symbol
• power sleep symbol.

And is the behavior consistent across different platforms?

Yes, the same symbols are shown as tofu boxes while in Private browsing on Ubuntu 20.04, macOS 11.7, and Windows 10. The issue is not reproducible in normal browsing.

On macOS, these symbols seem to be provided by the STIX fonts, which are present in the Supplemental fonts directory. So I think we could reasonably add these to the "base" font collection, just like we did for the supplemental Noto fonts in bug 1835271.

Haven't checked yet what fonts may be involved on Windows or Ubuntu.

Still reproducible on macOS 13 and Ubuntu 22.04 on the latest Nightly 116.0a1 while in private browsing.

Not an issue on Windows 10 though, whereupon rechecking, I noticed the presence of tofu boxes not only in private browsing mode but also in normal browsing mode across various browsers.

⏻

Can you see that??? I see that! I see that in this textarea, I see it in the DevTools when I inspect https://en.wikipedia.org/wiki/Miscellaneous_Technical but I don't see it on the page.

In Devtools, that symbol is being rendered with JetBrains. (I inspected DevTools using the Browser Toolbox.) This is a local font I have installed in ~/.fonts I don't know why it's used in DevTools. It's not my default font in Ubuntu. (In this textarea, it's being rendered by FiraGo, which is provided remotely.)

I cannot get JetBrains to be used by a website. (Test page) (This is with font-visibility set to 3.) Maybe FF doesn't look in ~/.fonts? It's used on https://fonts.google.com/specimen/JetBrains+Mono but maybe that's cause it's a downloaded font, I didn't dig in that closely. Although I have no idea why it's used in DevTools (I don't see anything in searchfox).

Okay, I think what is happening is that my local Firefox is trying anything to display the symbol, and since it's not in DejaVu Sans, it displays in JetBrains which I have locally.

I can only guess that there's something special about ~/.fonts that lets it be used in the Firefox UI (or maybe this even cascades down to the OS?) but doesn't let web content use it? Which is why my test page can't show it?

jfkthame - Do you ahve any idea what might be up with my ~/.fonts thing and this rendering for me in devtools but not letting me specify the font in web content?

Simona - could you show me what it is rendering with in a normal window by

1. First re-confirming that visibility=1 and visibility=3 do and don't show the power symbol (and if power symbol works but something else doesn't, switch to testing that new character)
2. Noting if visibility=2 shows it or not
3. Using Inspect Element on the (working) Power Symbol
4. Opening the Font menu in the far right pane using the drop-down arrow
5. Taking a screenshot of that

(In reply to Tom Ritter [:tjr] from comment #7)

Simona - could you show me what it is rendering with in a normal window by

• Tested on Ubuntu 22.04 and the power symbol is rendered.

1. First re-confirming that visibility=1 and visibility=3 do and don't show the power symbol (and if power symbol works but something else doesn't, switch to testing that new character)

• with visibility=1 the power symbol is not shown
• with visibility=3 the power symbol is shown.

2. Noting if visibility=2 shows it or not

• with visibility=2 the power symbol is still not shown.

3. Using Inspect Element on the (working) Power Symbol
4. Opening the Font menu in the far right pane using the drop-down arrow
5. Taking a screenshot of that

If I Inspect the symbol - JetBrains Mono is displayed in the Fonts tab. In the Computed tab for "font - family" - I see "sans serif".

For more details and screenshots, see this document, please don't hesitate to ni if additional info is needed.

Alright so she's got JetBrains Mono installed locally (I guess not in the same place as me?) and Firefox will use it for Web Content. I think I need Jonathan's help on this.

(In reply to Jonathan Kew [:jfkthame] from comment #4)

Haven't checked yet what fonts may be involved on Windows or Ubuntu.

On windows 11 I have every supplemental font as well as optional installs - https://learn.microsoft.com/en-us/typography/fonts/windows_11_font_list

The only tofu are: (power symbols were added in unicode v9.0 in 2016, and 23FF in v10 in 2017)

• 23FB POWER SYMBOL
• 23FC POWER ON-OFF SYMBOL
• 23FD POWER ON SYMBOL
• 23FE POWER SLEEP SYMBOL
• 23FF OBSERVER EYE SYMBOL

otherwise the entire Miscellaneous Technical block is using Segoe UI Emoji or Segoe UI Symbol which are both in kBaseFonts. So it seems as these aren't even supported on any windows releases